2 - 10,000 RPM meter

[glens5]

Accurate high resolution RPM meter using TTL CMOS I.C.'s
No micro-controller to program. The few I've tried had poor resolution below a couple hundred RPM. Bright LED display with a pot for fine adjustment.
I used this on the old horizontal mill I'd converted.
The magnets are Chinese neodymium from E-bay and only cost a few bucks. The large number of magnets are necessary for the resolution at very low RPM
This is my own design and seems to work just fine and I'm sure could be used in other applications.